How to run Play in production mode?

There are several methods, the easiest way is to run play start instead of play run.

You can find more information on the documentation: Starting your application in production mode

While being in the sbt console, you can also run your app in Prod mode with

[my-first-app] $ testProd

Also useful is to use this command to prevent sbt exiting when pressing CTRL+D

[my-first-app] $ testProd --no-exit-sbt

In Play 2.6, testProd was renamed to runProd:

[my-first-app] $ runProd